The invention relates to implantable medical devices and, more particularly, to electrical leads for use with such devices.
Implantable medical devices (IMDs), such as implantable cardioverter/defibrillators (ICDs) and pacemaker/cardioverter/defibrillators (PCDs), can detect and administer therapy for a variety of conditions. These conditions include ventricular fibrillation (VF), atrial fibrillation (AF), tachycardia, and bradycardia.
Various types of transvenous pacing and cardioversion/defibrillation leads have been developed for use with IMDs. These leads are typically flexible to facilitate insertion and placement into the body of the patient, and are usually constructed with an outer polymeric sheath encasing a coiled wire conductor. The coiled wire conductor is typically attached at a distal end to a shank portion of a tip electrode. A proximal end of the coiled wire conductor is coupled to a lead connector end assembly.
Different manufacturers often produce implantable cardiac leads with lead connector end assemblies that match connector block terminals of IMDs from a common manufacturer. More recently, a number of manufacturers have adopted a single dimensional pacemaker connector standard known as the low-profile connector xe2x80x9cIS-1xe2x80x9d standard (ISO 5841-3:1992(E)) for bipolar in-line and unipolar lead connector end assemblies. Compatibility with the IS-1 standard ensures that leads made by one manufacturer can be interchangeably used in connection with an IMD made by a different manufacturer.
In some conventional lead systems, a lead body is implanted through a guide catheter, which is then pulled off the lead body after implantation. Typically, the electrical connector attached to the end of the lead body has a larger diameter than the lead body. As a result, in such lead systems, pulling the guide catheter off the lead body can be difficult. Moreover, some connectors do not implement the low- profile design of the IS-1 standard, making post-implantation removal of the guide catheter even more difficult. In lead systems implementing such high-profile connectors, the guide catheter used must have a larger diameter, making lead placement in some places, such as the coronary sinus, difficult.
The invention is generally directed to electrical connectors that can be attached to an implanted lead body. More particularly, various embodiments of the invention provide electrical connectors that have a compressible portion that expands to accept an inserted lead and then contracts around the lead to provide both an electrical and a springlike mechanical connection to the lead. In one embodiment, the connector has a fluted pin that collapses around the lead body when a set screw of the connector port is tightened. In another embodiment, a middle segment of a pin has indentations or slots that collapse around an inserted lead body. Both embodiments are compatible with the IS-1 standard for pacemaker leads.
The invention provides a number of advantages. For example, the electrical connector can be attached to the lead body after the lead body is implanted in the body of a patient. In lead systems in which the lead body is implanted using a guide catheter, attaching the connector to the lead body after implantation allows removal of the guide catheter before the connector is attached. Because the guide catheter does not have to overcome mechanical resistance imparted by the larger diameter of the connector compared to the lead body, removal of the guide catheter is facilitated.
One embodiment of the invention is directed to an electrical connector that includes a first portion that defines a channel for receipt of a medical lead. An electrically conductive collapsible portion is operatively coupled to the first portion and is arranged to collapse around a portion of the medical lead upon receipt of the medical lead in the channel.
In a specific embodiment, the collapsible portion comprises a proximal portion of the electrical connector that has longitudinal slots that cause the proximal portion to collapse around the portion of the medical lead when a set screw of a connector port is tightened. When tightened, the set screw applies a force to the proximal portion that causes the proximal portion of the connector to collapse around the lead.
In another specific embodiment, the collapsible portion comprises a middle portion of the electrical connector that is disposed between the first portion of the connector and a proximal portion of the electrical connector. The middle portion has a slot arranged to cause the middle portion to collapse around the portion of the medical lead. These connectors may be implemented as part of a lead system.
Another embodiment of the invention is directed to a method of attaching an electrical connector to a medical lead. The medical lead is implanted in the body of the patient. A portion of the medical lead is threaded through a distal portion of an electrical connector. Next, an electrically conductive collapsible portion of the electrical connector is caused to collapse around the portion of the medical Icad, for example, by tightening a set screw of a connector port to apply a force to the collapsible portion.
The above summary of the invention is not intended to describe every embodiment of the invention. The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.